Daikin OAC 003G Installation And Maintenance Manual page 18

Electrical Installation
• Control wiring—access to the VFD is through the fan
cabinet access door for single fans. Provide shielded cable
only as described in the VFD manual provided with the unit.
Route wire through panel so that it not interfere with any
other components or in the way of any access doors. Do not
drill through drip or drain pans. Refer to the VFD
installation manual provided with the unit for detailed
control wiring instructions.
18
• For multiple fans in parallel, the VFD(s) are mounted inside
of the electrical enclosure, which is mounted on the exterior
of the fan section. When multiple fan sections are provided
with multiple VFDs, they must be set up so that the fans
always start simultaneously and are set to ramp up and down
together. Do not attempt to run fans in parallel at different
speeds as this can result in uneven airflow that can cause
performance, sound, and vibration problems that can lead to
failure. Provided that the fan is capable of running fast
enough and the motor is sized appropriately, VFDs may be
operated up to a maximum recommended frequency of 90
Hertz for 1800 RPM and slower motors. Motors that are
3600 RPM may be operated up to a maximum speed of 4000
RPM or 66.7 Hertz provided the fan is rated that high.
Operation above 4000 RPM can damage motor bearings and
is not recommended.
Daikin IM 777-7